We are offering the π midrange horns in high grade birch, both from domestic and Baltic sources. Domestic birch is $145.00 each and Baltic is $160.00. I need to get those listed on the shopping cart 'cause we're already taken orders, but so far, we do it manually.The JBL 2012 is an excellent driver. You're right that the response graphs shown were done with an Eminence Delta 10. But the JBL 2012 can be used too, provides nice smooth response and good summing, and has a shorting ring which reduces distortion.
The Peavey CH-3 is a good horn, and you can expect it to perform well. I also like your choices for woofers. The systems you have described are very similar to the directions I've taken for π cornerhorns. Specific models and what goes in them is shown in the post called "Implementation." So I'm with you 100% on your choice to use a JBL or Eminence Magnum woofer.